import java.util.Scanner;
public class pp3_5
{
  public static void main(String []args)
  {
    double a,b,c,d,e,f,g,h,i;
    Scanner scan = new Scanner(System.in);

    System.out.println("enter the first number1:");
    a = scan.nextDouble();

    System.out.println("enter the sencond number2:");
    b = scan.nextDouble();

    System.out.println("enter the third number3:");
    c = scan.nextDouble();

    System.out.println("enter the fourth number4:");
    d = scan.nextDouble();
    
    e = a-b;
    f = c-d;
    g = Math.pow(e,2);
    h = Math.pow(f,2);
    i = Math.sqrt(g+h);
    System.out.println(i);
    }
  }  



